Co-catalyst and process for the preparation of organohalosilanes

Abstract

In a Rochow process, organohalosilanes are prepared by reacting metallic silicon particles with an organohalide in the presence of a copper catalyst and a co-catalyst. The invention uses as the co-catalyst a powder of co-catalyst active element-copper alloy containing substantial strain energy because this co-catalyst can reduce the activation time taken until a steady state is reached, which has been an outstanding problem in Rochow reaction, maintain the steady state over time and increase the selectivity of desired diorganodihalosilane for eventually increasing the yield based on the starting silicon.

1. A process for preparing organohalosilanes, comprising the step of reacting metallic silicon particles with an organohalide in the presence of a copper catalyst and a co-catalyst comprising a copper alloy powder which is an alloy of copper with at least one element selected from the group consisting of zinc, tin, antimony, phosphorus and aluminum and containing substantial strain energy so that the alloy, on air flow differential thermal analysis, exhibits an incipient heat generation temperature of up to 400° C. with an exothermic value of 1 to 80 cal/g
 wherein the alloy having substantial strain energy is obtained by a mechanical working of rolling or stamping 
 wherein the co-catalyst has a specific surface area of 0.1 to 2.0 m 2 /g as measured by the BET or air-permeability method. 
 
     
     
       2. The process of  claim 1 , wherein the copper alloy powder is a copper alloy foil powder, stamped copper alloy powder or microscopic copper alloy powder. 
     
     
       3. A process for preparing organosilanes, comprising the step of reacting metallic silicon particles with an organohalide in the presence of a copper catalyst and a co-catalyst comprising a copper alloy powder which is an alloy of copper with at least one element selected from the group consisting of zinc, tin, antimony, phosphorous and aluminum and containing substantial strain energy so that the alloy, on air flow differential thermal analysis, exhibits an incipient heat generation temperature of up to 400° C. with an exothermic value of 1 to 80 cal/g, wherein the alloy having substantial strain energy is obtained by a mechanical working of rolling or stamping and wherein the co-catalyst possesses the crystal lattice strain energy which relaxes at a temperature of up to 400° C., and has a specific surface area of 0.05 to 2.0 m 2 /g as measured by the BET or air-permeability method. 
     
     
       4. The process of  claim 1 , wherein the co-catalyst when heated in air, undergoes rapid surface oxidation concomitant with the relaxation of the strain energy. 
     
     
       5. The process of  claim 1 , wherein the alloy, on air flow differential thermal analysis, exhibits an incipient heat generation temperature of 150 to 400° C. 
     
     
       6. The process of  claim 1 , wherein the organohalosilane is diorganodichlorosilane.